Benzopyranopyridines as antiglaucoma agents

ABSTRACT

A method of reducing intra-ocular pressure in mammalian patients comprising administering to a glaucoma patient a therapeutically effective amount of a compound of the formula ##STR1## wherein, in the C ring, X is CH 2 , S, ##STR2## or NR 4  is H, loweralkyl, loweralkenyl, loweralkynyl or loweralkanoyl; n is an integer of 0 to 3; m is an integer of 0 to 3, or the C ring is a quinuclidine ring ##STR3## each R 1  is loweralkyl, and when taken together, the substituents R 1  R 1  form oxygen; R 2  is a C 1  -C 20  straight or branched chain alkyl, cycloalkyl, or ##STR4## wherein Y is a straight or branched chain alkylene group having from 1 to 10 carbon atoms, and each R 5 , R 6  and R 7  are the same or different members of the group consisting of H, halo or loweralkyl; R 3  is H or ##STR5## wherein Y&#39; is a straight or branched chain alkylene group having 1 to 8 carbon atoms, a is an integer from 1 to 4, b is an integer from 1 to 4, Z is CH 2 , O, S or NR 9  where R 9  is H or loweralkyl, with the provision that when Z is O, S or NR 9 , the sum of a and b is 3 or 4, and R 8  is H or loweralkyl; and the pharmaceutically acceptable salts thereof.

This is a division of application Ser. No. 948,058, filed Oct. 2, 1978,which is a division of application Ser. No. 711,749, filed Aug. 4, 1976now U.S. Pat. No. 4,136,183.

BACKGROUND OF THE INVENTION

This invention relates to the disease of glaucoma. Glaucoma is a diseaseof the eye, characterized by an increase of intra-ocular pressure andimpaired vision. In the adult, there are two types of glaucoma; (1)primary glaucoma which may be a wide angle or a narrow angle, and (2)secondary glaucoma which is a result of ocular disease. The majortreatment for glaucoma is the use of miotic agents which constrict thepupil and allow for better drainage. When the human eye has the diseaseof glaucoma, it is marked by an intense intra-ocular pressure, resultingin hardness of the eye, atrophy of the retina, cupping of optic disc andblindness. The problem is that if the glaucoma is not treated and thesymptoms reduced, blindness may result.

Glaucoma is responsible for about 14% of all new reported blindnesscases, and thus represents a significant economical problem which mustbe treated either medically or surgically. Various medications arecurrently available, but only a few are widely used, and the addition ofanother highly effective drug to the ophthalmological armemtarium wouldprovide a greater choice for medical therapy.

The present invention provides such drugs which are effective asantiglaucoma agents, i.e., effective in reducing the intra-ocularpressure in mammalian patients.

DETAILED DESCRIPTION OF THE INVENTION

This invention relates to an improved method of reducing theintra-ocular pressure in mammalian patients comprising administering toa glaucoma patient a therapeutically effective amount of a compound ofthe formula I ##STR6## wherein, in the C ring, X is CH₂, S, ##STR7## orNR₄ where R₄ is H, loweralkyl, loweralkenyl, loweralkynyl orloweralkanoyl; n is an integer of 0 to 3; m is an integer of 0 to 3, orthe C ring is a quinuclidine ring ##STR8## each R₁ is loweralkyl, andwhen taken together, the substituents R₁ R₁ form oxygen; R₂ is a C₁ -C₂₀straight or branched chain alkyl, cycloalkyl, or ##STR9## wherein Y is astraight or branched chain alkylene group having from 1 to 10 carbonatoms, and each R₅, R₆ and R₇ are the same or different members of thegroup consisting of H, halo or loweralkyl; R₃ is H or ##STR10## whereinY' is a straight or branched chain alkylene group having 1 to 8 carbonatoms, a is an integer from 1 to 4, b is an integer from 1 to 4, Z isCH₂, O, S or NR₉ where R₉ is H or loweralkyl, with the provision thatwhen Z is O, S or NR₉, the sum of a and b is 3 or 4, and R₈ is H orloweralkyl; and the pharmaceutically acceptable salts thereof.

As used herein, the term "loweralkyl" refers to C₁ -C₆ straight orbranched chain alkyl groups including methyl, ethyl, n-pentyl,iso-pentyl, neo-pentyl, n-propyl, iso-propyl, n-butyl, sec-butyl,tert-butyl, n-hexyl and the like.

The term "loweralkenyl" refers to straight and branched chain C₂ -C₆alkyl radicals from which a hydrogen atom has been removed from each oftwo adjacent carbon atoms to produce ethylenic unsaturation; e.g.,vinyl, allyl, methallyl, 1-pentenyl and the like.

The term "loweralkynyl" refers to C₂ -C₆ alkyl groups as defined above,from which two hydrogen atoms have been removed from each of twoadjacent carbon atoms to produce acetylenic unsaturation; e.g., ethynyl,propargyl, 2-butynyl, 1-pentynyl and the like groups.

The term "halo" includes chloro, fluoro, bromo and iodo.

The term "loweralkanoyl" refers to saturated monovalent, aliphaticradicals derived from a monocarboxylic acid, including straight orbranched chain radicals of from one to six carbon atoms including theformyl, acetyl, propionyl, α-methylpropionyl, butyryl, hexanoyl and thelike radicals.

"Cycloalkyl", as used herein, refers to cyclic saturated aliphaticradicals having three to eight carbon atoms in a ring, such ascyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl andcyclooctyl.

"Cycloalkylloweralkyl" refers to groups such as cyclopropyl-methyl,2-methylcyclobutyl and the like.

The term "alkyl" refers to straight and branched chain alkyl radicalshaving from one to twenty carbon atoms such as methyl, n-amyl,3-methyl-2-octyl, 2-nonyl, 2-eicosanyl and the like.

The term "pharmaceutically acceptable acid addition salts" refers tonon-toxic salts prepared by reacting the basic esters of thebenzopyranopyridines with an organic or inorganic acid, or by reactingthe benzopyranopyridines with the salt of an appropriate acid.Representative salts include the hydrochloride, hydrobromide, sulfate,bisulfate, acetate, valerate, oleate, laurate, borate, benzoate,lactate, phosphate, tosylate, citrate, maleate, succinate, tartrate,napsylate and the like.

When R₃ is hydrogen, the term "pharmaceutically acceptable salts" refersto the alkali earth, alkali metal, ammonia and substituted ammoniumsalts such as the sodium, potassium, aluminum, magnesium,benzylammonium, methylammonium, dimethylammonium and the like salts.

The following formulae illustrate the compounds useful in the practiceof this invention.

When X is NR₄ and n is 3, the compounds useful in the practice of thisinvention are represented by formula II ##STR11##

When the C ring is a quinuclidine ring and R₁ R₁ =0, the compounds arerepresented by formula (III) ##STR12##

When R₃ is hydrogen and X is NR₄ where R₄ is loweralkyl, the compoundsare prepared according to U.S. Pat. No. 3,576,798. When R₃ is ##STR13##the corresponding esters are prepared by equimolar amounts of thephenolic benzopyranopyridines with an appropriate acid or salt thereofin the presence of a carbodiimide such as dicyclohexyl carbodiimide anda suitable solvent such as methylene chloride, chloroform and the like.This reaction can be represented as follows: ##STR14##

Some of the heterocyclic acids which can be used in the process ofpreparing the esters of this invention are:

γ-piperidinobutyric acid,

γ-morpholinobutyric acid,

γ-(2-methylpiperidino)-butyric acid,

ζ-piperidininovaleric acid,

γ-pyrrolidinobutyric acid,

β-piperidinopropionic acid,

Γ-thiomorpholinobutyric acid, and

homopiperidinoacetic acid.

Reaction between the benzopyran starting material and the heterocyclicacid, or salt thereof, is readily effected by combining about equimolaramounts of the reactants and a slight excess of carbodiimide such asdicyclohexylcarbodiimide. The reaction proceeds readily at roomtemperature and is generally completed in about 4 to 20 hours. After thereaction is terminated, the reaction mixture can be filtered to removethe by-product by dicyclohexylurea, and the solvent can be distilled offusing a rotary evaporator. The residue can be directly crystallized froma suitable solvent such as benzene/ether or the residue can bechromatographed and the desired material isolated from the appropriatechromatographic fractions. If the basic esters are obtained, the acidaddition salts such as those named above, if desired, can be prepared bymethods well known in the art.

Compounds wherein R₄ is ##STR15## can be prepared according to thefollowing reaction scheme: ##STR16##

Compounds of formula II wherein R₃ is hydrogen and X is NR₄ wherein R₄is alkyl or cycloalkyl can be prepared according to the method describedin U.S. Pat. No. 3,576,798.

Compounds of formula III can be prepared according to the methoddescribed in U.S. Pat. No. 3,493,579.

The compounds that are effective as antiglaucoma agents according to thepresent invention include:

(A)5,5-Dimethyl-10-hydroxy-8-(3-methyl-2-octyl)-2-(2-propynyl)-1,2,3,4-tetrahydro-5H-[1]benzopyrano[3,4-d]pyridine.

(B)5,5-Dimethyl-10-[4-(1-piperidine)butyryloxy]-8-(3-methyl-2-octyl)-2-(2-propynyl)-1,2,3,4-tetrahydro-5H-[1]benzopyrano[3,4-d]pyridinehydrochloride.

(C)4,4-Dimethyl-9-[(4-hompiperidino)butyryloxy]-7-(3-methyl-2-octyl)-1,2,3,4-tetrahydrocyclopenta[c][1]benzopyranhydrochloride.

(D)5,5-Dimethyl-10-[αmethyl-1-piperidinebutyryloxy]-8-(3methyl-2-octyl)-2-(2-propynyl)-1,2,3,4-tetrahydro-5H[1]benzopyrano[3,4-d].

(E)5,5-Dimethyl-10-[2-methyl-(2-methylpiperidino)butyrloxy]8-(3-methyl-2-octyl)-2-(2-propynyl)-1,2,3,4-tetrahydro-5H[1]benzopyrano[3,4-d]pyridinedihydrochloride.

(F)5,5-dimethyl-10-hydroxy-8-[5-(4-fluorophenyl)-2-pentyl]2-(2-propynyl)-1,2,3,4-tetrahydro-5H-[1]benzopyrano[2,3-d]pyridine.

(G)1,4-ethano-5-oxo-10-[4-(1-piperidino)butyryloxy]-8-(3-methyl-2-octyl)-1,2,3,4-tetrahydro-5H[1]benzopyrano[3,4-d]pyridinehydrochloride.

(H)4-oxo-9-[1-(morpholine)butyrloxy]-7-(3-methyl-2octyl)-1,2,3,4-tetrahydrocycylopenta[c][1]benzopyranhydrochloride.

(I)5,5-Dimethyl-8-[5-(4-fluorophenyl)-2-pentyl]10-[4-(4-morpholine)-butyryloxy]-2-(2-propynyl)-1,2,3,4-tetrahydro-5H-[1]benzopyrano[3,4-d]pyridinehydrochloride.

(J)5,5-Dimethyl-8-[5-(4-fluorophenyl)-2pentyl]-10-[α-methyl-4-(morpholino)butyryloxy]-2-(2-propynyl)-1,2,3,4-tetrahydro-5H-[1]benzopyrano[3,4-d]pyridinedihydrochloride.

The following examples illustrate the activity of the compounds usefulin the practice of this invention.

EXAMPLE 1 Effect of Topical Application of the Present Compounds

In this test, unanesthetized male albino rabbits, weighing from 2-4 kg.,were used and placed in plexiglass restrainers (Plas Labs ModelXPL-502-AR). Then, the eyes of the rabbits were anesthetized by atopical administration of a 1% solution of lidocaine hydrochloride(approximately 0.1 ml.), and the intraocular pressure of the variouscompounds was measured with a Bausch and Lomb Applamatic Tonometer. Thetest compounds were instilled topically into the rabbit eye after firstbeing dissolved in distilled water and in a 50% solution of propyleneglycol in water. A volume of 0.1 ml. of a 0.1% solution was the amountadministered. Each compound was tested in at least 4 eyes from 4different rabbits. The results are shown below in Table I, where thepresent compounds are compared with pilocarpine and epinephrine.

                  TABLE I                                                         ______________________________________                                        EFFECTS OF TOPICALLY APPLIED COMPOUNDS                                        ON INTRA-OCULAR PRESSURE IN RABBITS                                                  Solu-                                                                              Percent Change At                                                          tion   30      60    90    120   180                                 Compound (%)    Min.    Min.  Min.  Min.  Min.                                ______________________________________                                        Pilocarpine                                                                            0.1    +6.0    +4.9  +6.6  +6.6  -1.3                                Epinephrine                                                                            0.1    +14.8   +3.4  +12.3 -2.5  -1.5                                (B)      0.1    -15.4   -26.9 -38.5 -50.0 -30.8                               (C)      0.1    +33.3   -4.2  +0.8  -41.7 -33.3                               (E)      0.1    -22.2   -5.6  -1.1  -16.7 -38.9                               (F)      0.1    -8.0    -43.0 -28.0 -23.0 -25.0                               (G)      0.1    -33.3   -47.6 -52.4 -23.8 -9.52                               (H)      0.1    -42.9   -50.0 -4.9  -42.9 -10.7                               (I)      0.1    -43.3   -50.0 -4.0  -23.3 -50.0                               (J)      0.1    -46.1   -26.9 -23.1 -34.6 -61.5                               ______________________________________                                    

As is shown in Table I, the compounds of the present invention areactive when applied topically more so than the standard or controlcompounds of pilocarpine and epinephrine. As a basis for activity, ithas been found that where the compound is topically applied and there isa reduction in the intra-ocular pressure of 20% or more, the compound isactive.

EXAMPLE 2 Effect of Oral Administration of Present Compounds

The procedure in this evaluation was the same as that described inExample I except that the compounds were placed into gelatin capsulesand administered orally. The results of the evaluation are provided inTable II below.

                  TABLE II                                                        ______________________________________                                        EFFECTS OF ORALLY ADMINISTERED COMPOUNDS                                      ON INTRA-OCULAR PRESSURE IN RABBITS                                                      Percent Change At                                                          Dose     30      60    90    120   180                                Compound                                                                              (mg./kg.)                                                                              Min.    Min.  Min.  Min.  Min.                               ______________________________________                                        (A)     10.0     -22.0   -18.0 -15   -5.0  -18.0                              (B)     10.0      -9.3    -6.5 -11.7 -2.8  -23.4                              ______________________________________                                    

We claim:
 1. A method of reducing intra-ocular pressure in mammalianpatients comprising administering to a glaucoma patient atherapeutically effective amount of a compound of the formula ##STR17##wherein, in the C ring, X is NR₄ where R₄ is H, loweralkyl,loweralkenyl, loweralkynyl or lower alkanoyl; n is an integer of 0 to 3and m is an integer of 0 to 3; each R₁ is loweralkyl and when takentogether the substituents R₁ R₁ form oxygen; R₂ is a C₁ -C₂₀ straight orbranched chain alkyl, cycloalkyl, or ##STR18## wherein Y is a straightor branched chain alkylene group having from 1 to 10 carbon atoms, andeach R₅, R₆ and R₇ are the same or different and are H, halo orloweralkyl; and R₃ is H.
 2. A method according to claim 1, wherein X isNR₄ where R₄ is --CH₂ C.tbd.CH; n is 2, m is 2; R₁ is CH₃ ; R₂ is##STR19## and R₃ is H.
 3. A method according to claim 1, wherein X isNR₄ where R₄ is --CH₂ C.tbd.CH; n is 2, m is 1, R₁ is CH₃ ; R₂ is##STR20## where Y is ##STR21## R₅ is F, and R₆ and R₇ are each H; and R₃is H.